Medical probe device with transparent distal extremity

ABSTRACT

A medical probe device for introduction by way of a natural body opening into a tubular internal anatomical part of the body includes an elongate member having proximal and distal extremities and a passageway extending from the proximal extremity to the distal extremity along a longitudinal axis, a transparent guide piece mounted on the distal extremity of the elongate member, the transparent guide piece having proximal and distal extremities and a bore therein defining a guide piece lumen extending from the proximal extremity of the guide piece distally at least part way to the distal extremity of the guide piece, the guide piece lumen being in communication with the passageway in the elongate member, an optical viewing element movable within the passageway of the elongate member and having a distal extremity movable within the guide piece lumen, a handle mounted on the proximal extremity of the elongate member, the distal extremity of the optical viewing element mounted within the guide piece lumen so that the distal extremity of the optical viewing element is movable in a longitudinal direction within the guide piece lumen between a distal position to permit viewing forward of the distal extremity of the guide piece within the body and a proximal position to permit viewing lateral to at least the distal extremity of the guide piece.

BACKGROUND

This invention relates generally to elongate medical devices insertableinto the body, which are provided with optical viewing apparatus bywhich a remote site within the body near the distal extremity of thedevice can be seen from outside the body. Particularly, the inventionrelates to medical devices insertable into the body by way of a naturalbody opening, which are provided with optical viewing apparatus and withmeans, situated near the distal extremity and manipulable from theproximal extremity, for treatment of an internal organ. Such devicesinclude for example transurethral catheter devices for treatment of theprostate.

Conventionally the distal extremity of such a device is introduced intothe body and is maneuvered remotely, by manipulation of controls outsidethe body, to the site within the body that is to be observed andtreated. Optical viewing apparatus in such devices typically providesfor illumination of part of the region near (typically forward of) thedistal extremity, and for conducting an image from the distal extremityto the proximal extremity, where the operator can view it.

Transurethral needle ablation devices having optical viewing capabilityand designed for treating the tissue of the prostate are described forexample in U.S. Pat. Nos. 5,370,675; 5,366,490; and 5,435,805; andInternational Patent Publication No. WO 96/22739. The optical viewingapparatus in these devices facilitates positioning the distal extremityof the device at the appropriate site within the urethra, byilluminating the interior of the urethra and providing the operator withan image of the urethra wall as the distal extremity of the device isadvanced within it toward the treatment site.

Many such procedures entail application of high-frequency electricalcurrent, microwave energy, radio frequency energy, acoustical energy orlaser energy to destroy cells in a target tissue. Significant damage toadjacent or surrounding tissues can result from application of thetreatment if the treatment means is not precisely positioned before theablating energy is applied. In a transurethral needle ablation procedurefor treatment of the prostate, for example, when the needle electrode ispressed against the urethral wall the tip of the needle may fail topuncture the urethral wall, so that even when the needle is fullydeployed it has not crossed into the prostate tissue. Application ofelectrical energy under these circumstances can result in severe traumato the urethra.

Accordingly, in some disclosed devices, the optical viewing apparatus isadditionally intended to address both a need to observe the progress ofthe distal extremity of the device to the treatment site, and a need tobe able to view the treatment means while the treatment is in progress.

For example, U.S. Pat. No. 5,435,805 is directed to a device (such as adevice for treatment of benign prostate hypertrophy) having opticalviewing capability for precise placement of the device which deliversthe therapeutic energy into targeted tissues while minimizing effects onsurrounding tissue. Particularly, U.S. Pat. No. 5,435,805 discloses amedical probe device having a stylet guide housing with at least onestylet port and means for directing a flexible stylet sideways outthrough the port into a target tissue, and a fiber optic viewingassembly, which has a viewing field extending forwardly and sidewardlyof the guide housing to permit viewing of the stylet as it is deployedsideways from the distal extremity of the guide housing. To provide anunobstructed view of the emerging stylet, in some embodiments a portionof the material of the guide housing is removed to form a transversedepression behind the stylet port. However, the urethral wall is flabby,and tends to collapse into the depression, obscuring the view forward.In other embodiments the guide housing is provided with a window; butsuch an arrangement is difficult to manufacture and provides onlylimited visibility.

SUMMARY OF THE INVENTION

We have discovered that medical probe devices can be made with acapability for excellent viewing both during placement of the distalextremity of the device at the treatment site and during the progress ofthe treatment, by providing the distal extremity of the device with atransparent guide piece having a longitudinal bore within which the tipof an optical viewing element can be positioned. In a more forwardposition the visual field permits observation in a forward direction,particularly useful during placement of the device, as the distalextremity is directed toward the treatment site. In a more rearwardposition the visual field includes an image of a distal portion of theguide part, permitting observation of a distal portion of the guidepiece and of its surroundings. The guide piece can additionally beprovided with means for guided deployment of a treatment element (suchas a stylet for application of radio frequency electrical energy, forexample), and the optical viewing element can be positioned within thelongitudinal bore in the transparent guide piece such that progress ofdeployment of the treatment element is within the visual field of theoptical viewing element. Proper deployment of the treatment element isthus assured by direct observation.

In one general aspect, the invention features a medical probe device forintroduction by way of a natural body opening into a tubular internalanatomical part of the body, including an elongate member havingproximal and distal extremities and a passageway extending from theproximal extremity to the distal extremity along a longitudinal axis, atransparent guide piece mounted on the distal extremity of the elongatemember, handle means mounted on the proximal extremity of the elongatemember, and an optical viewing element movable within the passageway inthe elongate member. The transparent guide piece has a bore thereindefining a guide piece lumen in communication with the passageway in theelongate member and extending from the proximal extremity of the guidepiece distally at least part way to the distal extremity of the guidepiece. The optical viewing element has a distal extremity movable withinthe guide piece lumen, and the handle means carries means for mountingthe distal extremity of the optical viewing element within the guidepiece lumen and for moving the distal extremity of the optical viewingelement in a longitudinal direction within the guide piece lumen betweendistal and proximal positions. The distal position provides a firstvisual field permitting viewing in a direction distal to the distalextremity of the guide piece, and the proximal position provides asecond visual field permitting viewing in a direction lateral to atleast the distal extremity of the guide piece.

In some embodiments the guide piece additionally includes a styletguiding channel having an opening on a surface of the guide piece, andthe device additionally includes a stylet that is slidably movable inthe stylet guiding channel. The handle means carries means for mountingthe stylet within the stylet guiding channel and for slidably moving thestylet within the stylet guiding channel through the opening. The styletguiding channel directs the stylet at an angle to the longitudinal axisof the elongate member as the stylet is slidably moved outward throughthe stylet guiding channel opening, and the distal extremity of thestylet is within the second visual field as the stylet emerges throughthe opening.

In preferred embodiments the material of which the transparent guidepiece is made has a refractive index in the range about 1.3 to about 1.7and a luminous transmittance at least about 80% as determined using ASTMD 1003 procedures in a 0.3 mm thick specimen of the material. In someembodiments the transparent guide piece is made of transparent polymermaterial, which may be one or a combination of a polymer such as apolymethylmethacrylate, cellulose acetate, a polycarbonate, apolyurethane, or a polyethyleneterephthalate; or a glass.

In some embodiments the device additionally includes within the styletguiding channel a guide tube within the lumen of which the stylet isslidably movable. Usually the guide tube is made of a materialcomprising metal, such as stainless steel. Usually, to reduce unwantedglare resulting from reflection from the inner surface of the styletguiding channel or from the outer surface of the guide tube, thesesurfaces have a matte finish, which may include a conversion coatingsuch as a black oxide coating.

We have further discovered that, employing a transparent guide piece atthe distal extremity of the device and a suitably adapted opticalviewing element, the operator can be provided with a split image showingsimultaneously a view (for example in a lower portion of a circularimage) in a forward direction and a view (for example in an upperportion of a circular image) in a lateral direction.

Accordingly, in a further aspect, the invention features a medical probedevice for introduction by way of a natural body opening into a tubularinternal anatomical part of the body, including an elongate memberhaving image-splitting means at its distal extremity, usually includinga planar surface inclined with respect to the optical axis of theoptical viewing element.

In a further general aspect, the invention features a medical probedevice for treatment of the prostate of a human male, the deviceincluding an elongate member having proximal and distal extremities anda passageway extending from the proximal to the distal extremity along alongitudinal axis, with handle means mounted on the proximal extremityand a transparent guide piece mounted on the distal extremity. Thetransparent guide piece has a bore which defines a guide piece lumenthat is in communication with the passageway in the elongate member,extending from the proximal extremity of the guide piece distally atleast part way to the distal extremity of the guide piece. The guidepiece includes a stylet guiding channel that is in communication withthe passageway in the elongate member, and that opens on a surface ofthe guide piece. The device additionally includes a stylet, slidablymovable in the stylet guiding channel, including a radio frequencyneedle electrode with a sharpened tip and a layer of insulating materialcoaxially disposed on the radio frequency needle electrode so that aportion of the radio frequency needle electrode is exposed. The handlemeans includes means for mounting the stylet within the stylet guidingchannel and for slidably moving the stylet within the stylet guidingchannel through the opening. The stylet guiding channel directs thestylet at an angle to the longitudinal axis of the elongate member asthe stylet is slidably moved outward through the stylet guiding channelopening. And the device additionally includes an optical viewing elementthat is movable within the passageway of the elongate member and thathas a distal extremity movable within the guide piece lumen. The handlemeans includes means for mounting the distal extremity of the opticalviewing element within the guide piece lumen and for moving the distalextremity of the optical viewing element in a longitudinal directionwithin the guide piece lumen between a distal position and a proximalposition. The distal position provides a first visual field permittingviewing in a direction distal to the distal extremity of the guide pieceand the proximal position provides a second visual field permittingviewing in a direction lateral to at least the distal extremity of theguide piece, and the distal extremity of the stylet is within the secondvisual field as the stylet emerges through the opening.

In some embodiments the device additionally includes means cooperativewith the handle means and with the means for mounting the distalextremity of the optical viewing element within the guide piece lumen,for reversibly locking the distal extremity of the optical viewingelement in each of the distal and the proximal positions. Usually, thelocking means includes a cam cooperative with a slot.

Additional features and advantages of the invention will be apparentfrom the following description in which the preferred embodiments areset forth in detail in conjunction with the accompanying drawings, andfrom the claims.

DETAILED DESCRIPTION

FIG. 1 is a sketch in a perspective view of an embodiment of a medicalprobe device of the invention.

FIG. 2 is a sketch in a side elevational view of the distal extremity ofthe embodiment of FIG. 1.

FIG. 3 is a sketch in a side elevational view as in FIG. 2 of atransparent guide piece of the invention.

FIG. 4 is a sketch in a plan view of the transparent guide piece of FIG.3.

FIG. 5 is a sketch in an exploded view of the handle means and proximalextremity of the optical viewing device, showing means according to theinvention for locking the longitudinal position of the optical viewingapparatus.

FIG. 6 is a sketch in a side elevational view of a transparent distalextremity capable in cooperation with an optical viewing device ofproducing a split image, according to the invention.

FIG. 7 is a sketch showing a split image hypothetically formed using thetransparent distal extremity as in FIG. 6.

The invention is here described in detail with specific reference toembodiments of transurethral medical probe devices useful in treatmentof the prostate. It will be appreciated that the invention is suitablyuseful in connection with other devices, insertable into the body, whichmay be provided with optical viewing apparatus and which are providedwith means manipulable from outside the body for observing and treatinga site within the body.

All publications cited herein, including patents, and all patentapplications cited herein are hereby incorporated by reference in theirentirety.

With reference now to FIG. 1, there is shown generally at 16 anexemplary embodiment of a probe according to the invention. Such probesare described, for example, in copending U.S. patent application Ser.No. 08/833,982 filed Apr. 11, 1997, and also in copending U.S. patentapplication Ser. No. 29/069,167 filed Apr. 11, 1997, and also incopending U.S. patent application Ser. No. 08/833,984 filed Apr. 11,1997, and also in copending U.S. patent application Ser. No. 08/377,600,filed Jan. 24, 1995. As described therein, probe 16 consists of a rigidelongate sheath 36 formed of a suitable material such as stainlesssteel. It is of a suitable size as for example 23 French and hasproximal and distal extremities 37 and 38 and a length approximately11". The proximal extremity 37 of the sheath 36 is rotatably mounted ona handle 41 which is sized so as adapted to be grasped by an adult humanhand. A knob 42 is provided on the proximal extremity 37 and is adaptedto be grasped by a finger of the hand as for example the thumb to permitrotational movement of the sheath 36 for a purpose hereinafterdescribed. The sheath 36 carries at least one and preferably first andsecond needle electrode assemblies 46 and 47 which are slidably mountedin the sheath 36 and which are directed through a transparent or clearrounded or bullet-shaped tip 51 in off axis or sidewise projectingpositions at divergent angles with respect to each other as for examplean angle ranging from 30°-60°. Each of the first and second needleelectrode assemblies 46 and 47 consists of a conductive metal electrode52 formed of a suitable material such as Nitinol and which is providedwith a sharpened tip. A sleeve 53 formed of an insulating material isprovided on each electrode and is slidably mounted with respect theretoso that predetermined lengths of the needle electrodes can be exposed inperforming the radio frequency ablation as hereinafter described.

The handle 41 is formed of a two part case or housing 56 formed of asuitable material such as plastic. The housing 56 is provided with aflat upper surface 57 on which sliders 58 and 59 are mounted which areprovided for controlling respectively the motion of the electrode 52 andthe sleeve 53 of the first needle assembly 46 and sliders 61 and 62 areprovided for controlling respectively the electrode 52 and the sleeve 53of the second needle electrode assembly 47. The sliders 58, 59 and 61and 62 are adapted to be grasped by the thumb of the hand while thehandle 41 is being held in the hand.

An optical viewing device 66 is slidably mounted in the handle 41 and ismovable between the first and second positions and in the first positionextending through the sheath 36 and through the transparent rounded tip51 so that viewing of the region distally of the tip can be explored anda second position in which it is retracted into the sheath but beingadjacent the transparent rounded tip 51 so that deployment of the firstand second needle assembles 46 and 47 can be observed.

The optical viewing device 66 includes an eye piece 67 through whichviewing can occur. It also includes a fitting 68 which is provided withan adapter 69 which is adapted to be connected to a suitable source oflight (not shown). It is also provided with another fitting 71 throughwhich an irrigation liquid as for example a saline solution can beintroduced. The liquid introduced passes through the sheath 36 and exitsthrough the tip 51 into the tissue to be ablated to provide a clearfield of view for viewing through the optical viewing device 66. Theliquid introduced can be aspirated through a plurality of holes 72provided in the sheath 36 and passing though the sheath and the housing56 where it can be aspirated through an aspiration port 73 connected toa suitable source of vacuum. Spaced apart marks 74 are provided on thesheath to indicate to the physician performing the ablation procedurethe length of deployment of the probe 16 into the urethra as hereinafterdescribed.

FIG. 2 shows in further detail the distal extremity 38 of elongatesheath 36, together with transparent guide piece 51 and needle electrodeassembly 46 consisting of conductive electrode 52 and insulating sleeve53. Transparent guide piece 51 has distal and proximal extremities 84,86. Proximal extremity 86 includes a shoulder 87 which abuts the end 88of the distal extremity 88 of elongate sheath 36 when a press-fitportion 89 of guide piece proximal extremity 86 is inserted thereto.

Needle electrode assembly 46 is shown in FIG. 2 partially deployed as ifit were entering the tissue to be treated (not shown in the Figs.). Thedistal extremity 80 of optical viewing device 66 is shown in FIG. 2 in afirst more distal position (broken lines, 81a), providing a first visualfield 83a permitting viewing in a direction distal to the distalextremity 84 of the transparent guide piece 51, and in second a moreproximal position 81b providing a second visual field 83b permittingviewing in a direction lateral to at least the distal extremity 84 ofthe guide piece, and including the electrode assembly 46.

Certain features of the transparent guide piece 51 are more clearly seenin FIGS. 3 and 4. Transparent guide piece 51 has a body 82, formed of atransparent material, having a bullet shape, with proximal and distalextremities 84, 86. Transparent guide piece body 82 has a longitudinalbore 90 describing a lumen 92 which has an opening 93 at the proximalend 86 of the guide piece body 82. Lumen 92 communicates with apassageway 94 that runs the length of the elongate sheath 36, and issuitably dimensioned to receive the distal extremity 80 of opticalviewing device 66. Bore 90 passes distally at least part way toward thedistal extremity 84 of transparent guide piece body 82; as shown in theFigs., bore 90 may pass all the way to, and may have an opening 95 on,the distal extremity 84.

As is disclosed in detail in copending U.S. patent application Ser. No.08/833,984 filed Apr. 11, 1997 (A-64374), for example, an irrigationliquid such as saline may be conducted from a fitting 71 through thesheath 36 to exit through the transparent tip or guide piece 51 to clearthe surroundings of the distal extremity of the device while in usewithin the body. The irrigation liquid can be conducted through thetransparent guide piece by way of a thin gap between the outer surfaceof the distal extremity 80 of the optical viewing device 66 and theinner surface 91 of the longitudinal bore 90. Where the outside diameterof the distal extremity 80 of the optical viewing device is about 0.100inches, for example, the inside diameter of the longitudinal bore 90 canbe about 0.136 inches.

Transparent guide piece body 82 additionally is provided with a pair ofchannels 100, 101, which have openings 104, 105 at the proximal end 95of guide piece body 82b; and openings 102, 103 at a surface of the guidepiece 51 toward the distal extremity 84. These channels receive styletguide tubes 106, 107. The lumens of the guide tubes 106, 107 communicatewith the passageway 94 in elongate sheath 36, and are dimensioned suchthat stylet assemblies 46, 47 are slidably movable from behind throughthem and out through openings 102, 103. The channels and the styletguide tubes within them are shaped so that they direct the styletassemblies 46, 47 at a desired angle off-axis into the surroundingtissue.

While the channels 100, 101 may by themselves serve to guide themovement of the stylet assemblies 46, 47, the guide tubes 106, 107 canprovide a superior internal surface for that purpose. The outer diameterof each stylet assembly can be slightly smaller than the inside diameterof the guide tubes, to provide unobstructed sliding movement of thestylet assemblies. Where the outside diameter of the stylet assembly isabout 0.043 inches, for example, the inside diameter of the guide tubescan be about 0.058 inches.

As will be appreciated, the quality of the image of the surroundings ofthe guide piece, viewable by the optical viewing apparatus through thetransparent guide piece material, depends upon the shape of the guidepiece (particularly, the angles of incidence of light at the surfaceinterface) and the optical qualities of the material from which theguide piece is made (particularly, the luminous transmittance and theindex of refraction of the material).

The transparent guide piece body is made of a material having a highluminous transmittance, to provide both for good illumination and arelatively unobscured image within the field of view of the opticalviewing device. Usually, the luminous transmittance of the guide piecebody material is greater than about 80%, as determined in a specimen 0.3mm thick using ASTM D 1003 procedures. Clearer images can be providedwhere the luminous transmittance of the guide piece body material isgreater than about 80%, still clearer where it is greater than about90%. Materials having sufficiently high luminous transmittance includetransparent polymers, such as acrylate polymers (includingpolymethylmethacrylate), cellulose acetates, polycarbonates,polyurethanes, and polyethyleneterephthalates; and glasses.

The outer surface of the transparent guide piece presents an interfacebetween the guide piece body material and the external milieu. To reducelens effects as well as internal reflection effects at the surfaceinterface, the guide piece body can be constructed of a material havingan index of refraction approximating that of the external milieu. Thefluids in the urethra, for example, which surround the distal extremityof a transulethral catheter device, have a refractive indexapproximately 1.33. Internal reflection and lens effects at the externalsurface of the transparent guide piece can be minimized by making theguide piece of a transparent material having a refractive index as nearto 1.33 as practicable. Transparent materials useful in such a milieuinclude transparent polymers (which can have refractive indices in therange about 1.3 to about 1.7), such as acrylate polymers (for examplepolymethylmethacrylate), cellulose acetates, polycarbonates,polyurethanes, and polyethyleneterephthalates; and glasses.

To the extent that the refractive index of the transparent guide piecematerial is not matched to that of the surrounding milieu, some degreeof internal reflection at the interface can be expected. As a matter ofgeneral optical principle, the degree of internal reflection dependsupon the extent of the mismatch and upon the angle of incidence of thelight, both of which can be readily determined for any material and anylight path. Accordingly, a preferred shape for the transparent guidepiece is one in which the extent of undesired internal reflection isminimized.

The transparent guide piece may be made by any of a variety oftechniques, known in the art, including molding and casting andmachining and combinations of molding and casting and machining. Mostconveniently for example, the guide tubes can be shaped and positionedwithin a mold, and the transparent guide piece material can then be castor molded around the guide tubes. The bore for the optical viewingdevice can either be molded or cast, or drilled after the guide piecebody has hardened.

With further reference to FIGS. 2, 3 and 4, the operation and use of aninsertable elongate medical device having a transparent guide pieceaccording to the invention may now be briefly described as follows.

Let it be assumed that the apparatus has been prepared for carrying outa tissue ablation for treatment of a benign prostatic hypertrophy.Accordingly, light energy is being supplied to the fitting 69. Liquid isbeing supplied to the fitting 71 and a vacuum has been placed incommunication with the port 73. Let it be assumed further that there hasbeen appropriate preparation of the patient for the procedure. The probe61 is then introduced by way of the penis into the urethra of thepatient. As the probe is advanced through the urethra, the progress ofthe distal extremity can be directly observed through the eyepiece 67,and the progress is continued until the transparent guide piece 51 isappropriately located in the region of the prostate to be treated, whichsurrounds the urethra. This viewing is accomplished by having theoptical viewing device 66 in its forwardmost position, as shown forexample at 81a in FIG. 2, so that the image the operator sees at theeyepiece 67 is provided by the field of view outlined at 83a, distal tothe extremity 84 of the transparent guide piece 51. Once the appropriatelocation at the prostate has been reached, the optical viewing device 66can be retracted slightly (10 mm may be a suitable retraction distance)so it is in a more proximal position, indicated for example at 81b inFIG. 2. In this position the image the operator sees at the eyepiece 67is provided by the field of view outlined at 83b, just proximal to thedistal extremity of the guide piece, and proximal to the openings 102,103 so that deployment of the needle assemblies 46 and 47 can beobserved. This deployment is accomplished by appropriate positioning ofthe sliders 58 and 61 to cause the distal extremities of the needleelectrodes 46 and 47 to project sidewardly or off axis through theurethral wall and into the selected lobe of the prostate to be treated.As soon as the needle electrode assemblies 46 and 47 have been advancedas far as desired into the prostate, the sliders 59 and 62 can be movedto cause retraction of the sleeves 53 surrounding the electrodes 52 toexpose predetermined lengths of the electrodes within the prostatictissue while still retaining the insulating sleeves so that they extendslightly beyond the urethral wall so as to protect the urethral wallfrom radio frequency ablation.

Then the electrical energy can be applied to disrupt the tissue withinthe prostate lobe without risk of exposing and causing trauma tosurrounding tissues. Once the needle ablation has been completed,sliders 58 and 61 and 59 and 62 can be moved as appropriate to retractthe needle assemblies 46 and 47 back into the guide tubes 106, 107within the guide piece 51. Device 16 is then withdrawn from the urethra.

FIG. 5 shows a simple locking mechanism in the handle 41, for readilyensuring that the distal extremity of the optical viewing device is heldsecurely in the first or second positions.

FIG. 5 shows an exploded view of portions of the handle 41 and theproximal extremity 120 of the optical viewing device 66. Locking lever110 is rotatable about the longitudinal axis of the optical viewingapparatus, and has a cam portion 112 engageable with one of a pair ofdetents 114, 116 in the subjacent upper surface 118 of handle 41. Forexample, to lock the optical viewing apparatus in the more distalposition, the optical viewing device 66 is slid distally until the camportion 112 is aligned with the more distal detent 114 and then thelever 110 is rotated (for example as shown by arrow 110') so that thecam 112 engages detent 114. The optical viewing apparatus may bewithdrawn to the more proximal position, by rotating lever 110 todisengage cam 112 from detent 114 and sliding the optical viewingapparatus in a proximal direction until the locking mechanism is alignedwith detent 116, and then rotating the lever 110 so that cam 112 engagesdetent 116. When the optical viewing apparatus is in this position, itsdistal extremity is in a correspondingly more posterior position, as forexample 81b in FIG. 2, so that the image carried to the eyepiece 67 isprovided by the field of view shown in outline at 83b in FIG. 2.

The distance between the forward edges 115, 117 of detents 114, 116establishes the longitudinal displacement of the distal extremity of theoptical viewing apparatus which may be, for example, about 10 mm.

As will be appreciated, the invention as described above provides forviewing simultaneously both in a direction distal to the distalextremity of the guide piece, and in a direction (through thetransparent body of the guide piece) lateral to the distal extremity ofthe guide piece, when the distal extremity of the optical viewingapparatus is in a more proximal position.

Further, as noted above, some degree of internal reflection can beexpected to occur at the interface at the surface of the guide piecebody, owing to the fact that there is a refractive index mismatchbetween the guide piece body material and the fluids surrounding theguide piece. And, as noted above, to the extent that internal reflectionmay be undesirable, for example because it may produce a glare thatinterferes with image quality, the guide piece body material may beselected to minimize the refractive index mismatch, and the shape of theguide piece surface may be designed so to avoid unwanted internalreflection.

However, we have discovered that the internal reflection property of thematerial can be exploited to provide a split image, viewable at theeyepiece. Such a split image consists in part of a distal view, and inpart of a lateral view, principally to one side of the longitudinal axisof the optical viewing apparatus. This is accomplished by providing thedistal extremity of the transparent guidepiece with a planar face,inclined at an oblique angle with respect to the longitudinal axis ofthe optical viewing apparatus. As a result of this configuration, somelight, coming from points normally laterally outside the field of viewof the optical viewing device, is reflected toward the optical viewingdevice from the inner side of the interface formed by the planar face,while some other light coming from points normally within the field ofview of the optical viewing device, are reflected or refracted at theinterface such that they do not reach the optical viewing device.

This effect has been proven in principle using a device shown in FIG. 6.There is shown a rod lens element 132 having a distal face 134, which inthe example shown is perpendicular to the longitudinal axis 130 of theoptical viewing device, and a transparent tip 136 having a generallycircular cross section about the longitudinal axis 130 and a planar face138 that is inclined at an oblique angle θ with respect to thelongitudinal axis 130. The planar face 138 provides an interface havingan inner side 137 and an outer side 139. Transparent tip 136 isconstricted of a material having a refractive index greater than that ofthe fluid in the milieu (adjacent the outer side 139) that bathes theface 138. As a result of the refractive index mismatch at the planarface, internal reflection effects cause internal reflection of certainof the light rays that are incident on the inner side 137 of theinterface. Particularly, as a matter of general optical principle, lightrays that meet the inner side 137 at an angle of incidence less than thecritical angle are reflected in a proximal direction, and some of theseare directed toward the face 134 of rod lens element 132 (for example,rays 140, 141); while rays that meet the inner side 137 at an angle ofincidence greater than the critical angle either pass through theinterface (for example, rays 142, 143) or pass through in part and arereflected in part (for example, rays 144, 145). As a consequence, theeffective field of view toward one side of the longitudinal axis 130(that is, toward the inner side 137 of the interface provided by theface 138) is substantially widened beyond the peripheral limit 183provided by the rod lens itself, so that the image toward that side ofthe device includes at its margin greater portions of the surroundings.

Light rays that are traveling parallel or approximately parallel to theface 138 on either side of the interface (for example, rays 146, 147)are not directed toward the face 134 of the rod lens element, and do notform part of the image.

Light rays that are incident upon the outer side 139 of the interface,that is, light rays coming from more distal directions and from lateraldirections toward the opposite side of the longitudinal axis 130, areeither reflected or are refracted at the interface; some of these rays(for example, rays 148, 149) reach the face 134 of the rod lens element.

As will be readily appreciated from the foregoing description, the shapeof the resulting image depends upon the angle θ, and the refractiveindices of the external milieu and of the material from which the tip136 is made.

Transparent tip 136 may be formed of any suitably transparent materialhaving an index of refraction higher than that of the external milieu.Suitable transparent materials include, for example, transparentpolymers. A polycarbonate having a refractive index about 1.58 may beparticularly suitable for a tip having a face 138 inclined at an obliqueangle θ of about 30°. A sketch of a hypothetical image resulting from atip made of such a polycarbonate in such a configuration and conductedby a rod lens element to an eyepiece is shown in FIG. 7. The generallycircular image 150 includes a lateral image portion 152 of ahypothetical object 151 and a distal image portion 154 of a hypotheticalobject 153.

The angle θ will be determined on the basis of general opticalprinciples, taking account of the respective indices of refraction ofthe material of which the tip is made and of the surrounding fluid(which may, for example, be saline), and in view of the positions of theobjects that it is desired to bring into the image. Preferably, theplane is inclined to the optical axis of the optical viewing device atan angle less than or equal to the critical angle, which may be readilycalculated for any combination of materials.

As will be appreciated, portions of the tip 136 other then the face 138can be shaped other than as shown in FIG. 6. In particular, atransparent guide piece 51 as shown for example in FIGS. 2-4 can beformed to exploit the principle demonstrated by the operation of tip136, by providing the transparent guide piece 51 with a planar distalsurface inclined at an oblique angle with respect to the longitudinalaxis of the distal extremity. Such a guide piece could operatesubstantially as described above with reference to FIGS. 2-4 and,additionally, could provide for simultaneous split viewing.

Where a transparent guide piece is so shaped to provide a split view,the distal extremity of the optical viewing device need not necessarilybe moved longitudinally in order to provide the desired range of lateraland distal views and, accordingly, the transparent guide piece need notnecessarily be provided with a longitudinal bore.

It is apparent from the foregoing that the invention provides medicalprobe devices that have a capability for excellent viewing both duringplacement of the device at the treatment site and during the progress ofthe treatment. Where the device is a transurethral catheter fortreatment of the prostate, the invention enables precise location of thedevice at the site, and for visual monitoring of the deployment of thetreatment means, to ensure that the treatment will be effective in thetarget tissues, and will not damage surrounding tissues.

Other embodiments are within the claims. For example, the inventionincludes devices that are introduced into the body by other routes thanthe urethra, and devices that are intended for treatment of tissues ororgans other than the prostate. And, for example, the invention includesdevices useful for observation of particular sites within the body,whether or not used for treatment as well. And, for example, theinvention includes devices in which the treatment means employsapplication of energy other than electrical energy for ablation oftissue, and in which the treatment means effects removal or reduction oftissues other than by application of energy to the target tissue.

What is claimed is:
 1. A medical probe device for introduction by way ofa natural body opening into an internal cavity of a body to a treatmentsite, comprising an elongate member having proximal and distalextremities and a longitudinal axis and a passageway extending from saidproximal extremity to said distal extremity along the longitudinal axis,a stylet slidably mounted in said passageway of the elongate member, aguide piece of a rigid transparent material mounted on said distalextremity of said elongate member, said guide piece having an outersurface provided with an opening therein and a bore extending throughthe guide piece to the opening, said bore in the guide piece being incommunication with said passageway in said elongate member, handle meansmounted on the proximal extremity of said elongate member for advancingthe distal extremity of said elongate member through the natural bodyopening so that the guide piece is in the cavity adjacent the treatmentsite, a guide tube disposed in the bore for directing the styletsidewise of the longitudinal axis through the opening into the treatmentsite and an optical viewing device mounted within said passageway ofsaid elongate member and having a distal extremity disposed within saidguide piece for viewing the stylet through the transparent material ofthe guide piece as the stylet is advanced from the opening into thetreatment site.
 2. The device of claim 1 wherein said guide piece isprovided with an additional bore which extends longitudinallytherethrough and wherein said optical viewing device is movable in saidadditional bore from a proximal position for viewing said stylet throughthe transparent material of said guide piece as the stylet is advancedfrom the opening into the treatment site and a distal position forviewing forwardly of said guide piece for facilitating advancement ofthe distal extremity of said elongate member through the internal cavityto the treatment site.
 3. The device of claim 1 wherein said transparentmaterial of said guide piece has a refractive index ranging about 1.3 toabout 1.7.
 4. The device of claim 1 wherein said transparent material ofsaid guide piece has a luminous transmittance of at least about 80% asdetermined in a specimen 0.3 mm thick using ASTM D 1003 procedures. 5.The device of claim 4 wherein said transparent material of said guidepiece has a luminous transmittance of at least about 90% as determinedin a specimen 0.3 mm thick using ASTM D 1003 procedures.
 6. The deviceof claim 1 wherein said transparent material of said guide piece is atransparent polymer.
 7. The device of claim 6 wherein said transparentpolymer is one or a combination of an acrylate polymer, a celluloseacetate, a polycarbonate, a polyurethane, and apolyethyleneterephthalate.
 8. The device of claim 6 wherein saidtransparent polymer comprises a polyurethane.
 9. The device of claim 6wherein said transparent polymer comprises polymethylmethacrylate. 10.The device of claim 6 wherein said transparent polymer comprises apolycarbonate.
 11. The device of claim 6 wherein said transparentpolymer comprises a cellulose acetate.
 12. The device of claim 1 whereinsaid guide tube is made of metal.
 13. The device of claim 12 whereinsaid metal is stainless steel.
 14. The device of claim 1 wherein thebore is formed by an inner surface of said guide piece, at least aportion of the inner surface having a matte finish for inhibitingundesirable reflections within said guide piece.
 15. The device of claim1 wherein said guide tube has an outer surface provided with a mattefinish for inhibiting undesirable reflections within said guide piece.16. The device of claim 14 wherein said matte finish comprises aconversion coating.
 17. The device of claim 15 wherein said matte finishcomprises a conversion coating.
 18. The device of claim 1 wherein saidguide piece has image-splitting means for permitting said opticalviewing device to view both sidewise and forwardly of said guide piece.19. The device of claim 18 wherein said image-splitting means comprisesa planar end surface inclined with respect to the longitudinal axis. 20.The device of claim 18 wherein said image splitting means permits saidoptical viewing device to simultaneously view sidewise and forwardly ofsaid guide piece.
 21. A medical probe device for treatment of a prostateof a human male having a bladder with a base with a urethra formed by aurethral wall extending into the base of the bladder with the tissue ofthe prostate surrounding the urethra near the base of the bladdercomprising an elongate probe member having proximal and distalextremities and a longitudinal axis and a passageway extending from saidproximal extremity to said distal extremity along the longitudinal axis,the elongate probe member having a length so that when the distalextremity is disposed in the urethra in the vicinity of the prostate theproximal extremity is outside the urethra, handle means coupled to saidproximal extremity of said elongate probe member for introducing saiddistal extremity of said elongate probe member into the urethra, astylet slidably mounted in the passageway of the elongate probe member,the stylet including a conductive radio frequency electrode and a layerof insulating material disposed around the conductive radio frequencyelectrode but exposing a distal portion of the conductive radiofrequency electrode, a guide piece of a rigid transparent materialmounted on said distal extremity of said elongate probe member, saidguide piece having a proximal extremity and a rounded distal end and aninternal curved surface for directing the stylet sidewise of thelongitudinal axis into the tissue of the prostate, said guide pieceprovided with a bore extending from said proximal extremity of saidguide piece through said rounded distal end of said guide piece, anoptical viewing device mounted within said passageway of said elongateprobe member and having a distal extremity movable longitudinally withinthe bore of said guide piece from a proximal position for viewing thestylet extending from said guide piece sidewise of the longitudinal axisand a distal position for viewing forwardly of said guide piece tofacilitate placement of said guide piece in the urethra.
 22. The medicalprobe device of claim 21 further comprising means cooperative with saidhandle means for reversibly locking said optical viewing device in eachof said proximal and distal positions.
 23. The medical probe device ofclaim 22 wherein said locking means comprises a cam cooperative with adetent.
 24. A medical probe device for introduction by way of a naturalbody opening into an internal cavity of a body, comprising an elongateprobe member having proximal and distal extremities and a longitudinalaxis and a passageway extending from said proximal extremity to saiddistal extremity along the longitudinal axis, handle means coupled tothe proximal extremity of said elongate probe member, an optical viewingdevice mounted in the passageway of said elongate probe member andhaving a distal extremity with a field of view and a guide piece of arigid transparent material mounted on said distal extremity of saidelongate probe member, said guide piece having a distal surface inclinedwith respect to the longitudinal axis and disposed within the field ofview of said optical viewing device, said distal surface being at leastpartially reflective when disposed within the internal cavity forpermitting the optical viewing device to view sidewise of thelongitudinal axis and being at least partially transmissive whendisposed within the internal cavity for permitting the optical viewingdevice to view forwardly of said guide piece.
 25. The medical probedevice of claim 24 wherein said distal surface is planar.
 26. Themedical probe device of claim 24 for use in an internal cavity providedwith fluid therein having an index of refraction wherein the transparentmaterial of said guide piece has an index of refraction greater than theindex of refraction of said fluid.